Hot flashes or flushing occur commonly in menopausal women. This is characterized by a sudden onset of warmth in the face and neck and often progressing to the chest. Such an episode generally lasts several minutes and is evidenced by a visible flushing of the skin. Often such episodes are accompanied by sweating, dizziness, nausea, palpitations and diaphoresis. Such symptoms can disrupt sleep and interfere with the quality of life. Although the cause of hot flashes are not completely understood, they are thought to be a disorder of thermoregulation resulting from a transient lowering of the hypothalamic temperature regulatory set point (Kronenberg et al., "Thermoregulatory Physiology of Menopausal Hot Flashes: A Review," Can. J. Physiol. Pharmacol., 65:1312-1324 (1987)). In post-menopausal woman, the cause of such hot flashes is believed to be a consequence of declining estrogen levels. Thus, it is not surprising that hot flashes also occur in a high percentage of women taking the anti-estrogen drug tamoxifen.
Men may also have hot flashes following androgen-deprivation therapy (from bilateral orchiectomy or treatment with a gonadotrophin-releasing-hormone agonist) for metastatic prostate cancer.
Although estrogen replacement therapy is the most direct and effective treatment for hot flashes in women, there are women in whom such therapy is contraindicated, i.e., women with breast cancer or a strong family history of breast cancer, a history of clotting, severe migraine, or who are averse to taking the drug.
In these women, there are alternative medications to prevent or treat the serious consequences of menopause, such as osteoporosis and raised serum lipid levels. Included in this category are the selective estrogen-receptor modulators (SERMs), such as raloxifene (see U.S. Pat. No. 5,534,526 to Cullinan), which selectively bind to and activate the estrogen receptors of some tissues such as bone, and block the receptors of others, i.e., breast and uterus. In so doing, they lack the negative impact that prolonged estrogen therapy may have on these organs. However, in contrast to estrogen, SERMs are not as effective in preventing hot flashes.
Other than estrogen-replacement therapy, there are no effective means to alleviate hot flashes. Low dose oral megestrol acetate, a progestational agent, was shown to reduce the frequency of hot flashes in both men and women in a short term study (Loprinzi et al., "Megestrol Acetate for the Prevention of Hot Flashes," N. Engl. J. Med. 331:347-351 (1994)). However, chronic adrenal insufficiency can be a side effect of low dose megestrol acetate when taken long term. Transdermal clonidine, a centrally active .alpha.-agonist, had only a moderate effect on the frequency and severity of hot flashes in tamoxifen-treated women (Goldberg et al., "Transdermal Clonidine for Ameliorating Tamoxifen-induced Hot Flashes," J. Clin. Onc. 12:155-158 (1994)).
Accordingly, there is a need for an alternative method of treating symptoms of hormonal variation, including hot flashes, which overcomes the deficiencies in the relevant art.